The present invention relates to limited slip differentials, and more particularly, to such differentials of the type referred to as locking differentials, having means for retarding differentiating action, and actuating means for actuating the retarding means.
Limited slip and locking differentials of the type to which the present invention relates typically include a gear case defining a gear chamber and disposed therein, a differential gear set including at least one input pinion gear and a pair of output side gears. A clutch pack is typically disposed between one of the side gears and an adjacent surface of the gear case, such that the clutch pack is operable to retard, or even prevent, rotation between the gear case and the side gears. In a locking differential, disposed between the clutch pack and its adjacent side gear is a cam means, operable to engage the clutch pack upon relative rotation of the cam members.
In many limited slip and locking differentials, some sort of actuating mechanism is provided to actuate or move the clutch pack to its engaged condition. One of the current trends in the field of vehicle traction modifiers involves the desire to be able to actuate the clutch packs in response to an external signal, rather than in response to the sensing of a predetermined speed differential as has typically been the case in the prior art.
U.S. Pat. No. 4,583,424 illustrates a locking differential in which the clutch is actuated by an actuator of the piston-cylinder type. The device illustrated in U.S. Pat. No. 4,583,424 may be generally satisfactory from an operational standpoint, but the overall device is excessively complex, requiring fluid passages and expensive seal arrangements.
Another prior art device is shown in U.S. Pat. No. 3,133,454, which illustrates a locking differential in which the locking is accomplished electromagnetically, in response to an input electrical signal. This device is also excessively complex, requiring electromagnetic coils within the differential case, and a substantial increase in the total number of parts.